*{
    margin: 0;
    padding: 0;
}
ul{
    list-style: none;
}
a{
    text-decoration: none;
}
#container{
    position: relative;
    width: 1000px;
    height: 440px;
    margin: 20px auto;
    overflow: hidden; /*溢出隐藏：只显示一张图片*/
}
#container .parent{
    position: absolute;
    width: 5000px; /*整个图片层长度：500*5=2500*/
    height: 440px;
}

#container .parent li{
    float: left;
    width: 1000px;
    height: 100%;
}
#container .parent li img{
    width: 100%;
    height: 100%;
}
#container .btnLeft,
#container .btnRight{
    width: 30px;
    height: 30px;
    background-color: #9E9E9E;
    border-radius: 20%;
    opacity: 80%;
    position: absolute; /*包含块为图片显示层container*/
    top: 0;
    bottom: 0;
    margin: auto;
    font-size: 20px;
        color: #f40;
        text-align: center;
        line-height: 30px;
}
#container .btnLeft{
    left: 10px;
}
#container .btnRight{
    right: 10px;
}
#container .btnLeft:hover,
#container .btnRight:hover{
    opacity: 90%;
    cursor: pointer;
}
/*蒙层*/
#container .modal{
    width: 100%;
    height: 40px;
    background: rgba(0,0,0,.3);
    position: absolute;
    left: 0;
    bottom: 0;
    line-height: 40px;
    padding: 0 40px;
    box-sizing: border-box;
}
#container .modal .title{
    float: left;
    color: #fff;
    font-size: 12px;
}
#container .modal .dots{
    float: right;
    position: absolute;
    bottom: 10px;
    left: 425px;
}
#container .modal .dots li{
    width: 15px;
    height: 15px;
    border-radius: 50%;
    float: left;
    /*可以使用行块盒*/
    /*display: inline-block;*/
    margin: 0 5px;
    cursor: pointer;
}
.clearfix::after{
    content: "";
    display: block;
    clear: both;
}
.on{
    background-color:#31c27c;
}
.off{
    background-color: gray;
}